Paraffin bath

ABSTRACT

A paraffin bath apparatus for melting paraffin used in therapeutic applications is disclosed. The paraffin bath apparatus comprises a housing having a base, a sidewall and upper opening. An inner tub is formed of a temperature resistant polymeric material is a generally cup shaped member having a bottom wall, an upstanding wall and an open top. The inner tub is received within the upper opening of the housing with the bottom wall of the inner tub overlying the base of the housing. The heating element is located between the inner tub and the housing for providing heat to the inner tub sufficient to melt the paraffin but below the temperature that would adversely affect the polymeric material forming inner tub. A thermostatic sensor is disposed between the inner tub and the housing and is electrically connected to the heating element to control the heat provided to the inner tub. A temperature indicating element may be provided in the inner tub and placed in contact with paraffin melted in the inner tub. The temperature indicating element provides a visual indication that the paraffin in the tub is within a predetermined temperature range and is visible through the melted paraffin.

This is a continuation of application(s) Ser. No. 09/523,506 filed onMar. 10, 2000, now U.S. Pat. No. 6,184,500.

TECHNICAL FIELD

The present invention relates to a therapeutic paraffin bath appliance.

BACKGROUND ART

Paraffin baths are used in therapeutic procedures, particularlyprocedures relating to the treatment of hand and foot treatments forarthritic and dermatologic conditions. In the treatment of arthritis orfor moisturizing skin a person may be directed to place their hand orfoot in a paraffin bath. In a paraffin bath, solid paraffin is heated toits melting point. The person may remove their hand or foot from thebath leaving a coating of paraffin applied to their skin. This procedurecan relieve arthritic pain. This procedure may also be used formoisturizing the skin on a person's hand or foot.

Paraffin baths are normally provided with a metallic inner tub that isreceived in an outer housing with heating elements attached to orlocated adjacent the metallic inner tub. Paraffin baths having ametallic inner tub are relatively costly to manufacture which adds tothe ultimate cost to consumers of such units.

An important aspect of paraffin bath appliances is the heating control.Some prior art paraffin baths have been provided with a costlyelectronic controller.

The heating system should be failsafe in that it should not be permittedto overheat. Prior art paraffin baths do not have a temperatureindicator reflecting the temperature of the melted paraffin. Anotherdisadvantage of some prior art paraffin baths is that a thermostat couldpossibly fail or the unit may be subject to temperature fluctuation ornonuniform heating of the paraffin in the bath.

When the paraffin bath is not in use, it is desirable to protect theparaffin from becoming contaminated.

These and other disadvantages encountered by prior art paraffin bathsare addressed by the paraffin bath made according to the presentinvention as will be understood from the following summary of theinvention.

DISCLOSURE OF INVENTION

A therapeutic paraffin bath designed for use by consumers, medicaloffices or physical therapy clinics is preferably durable and reliableas well as being easy to operate. A paraffin bath should also have arapid heating capability so that it is not necessary to wait for anextended period of time for the paraffin to melt and reach the desiredtemperature for treatment.

It is also preferable to provide temperature control within a range ofpotential treatment temperatures. According to the invention, a simplefailsafe temperature indicator is provided that permits a consumer orhealth professional to directly read the temperature of the paraffin inthe bath.

The therapeutic paraffin bath preferably includes dual heating elementsthat are capable of rapidly heating the paraffin in the bath. Evenheating of the paraffin prevents hot spots and cold spots within thebath.

The temperature control is preferably provided by a reliable andinexpensive adjustable thermostat. The thermostat preferably is providedwith a conductor strip through which temperature is monitored. Athermostatic fuse is also preferably provided as a safety mechanism inevent that the thermostat control fails or the unit overheats. Thethermostatic fuse would open if a overheating condition is sensed andcuts off power to the paraffin bath heating elements.

The therapeutic paraffin bath of the present invention preferablyincludes a plastic inner tub that is heated by means of two separateheating elements. The heating elements are a rope type, or braided,heating elements sandwiched in aluminum foil. One heating elementextends about the perimeter of the plastic inner tub. A second heatingelement is provided in the floor of the unit adjacent the bottom of theinner tub.

A removable strainer is preferably provided that may be placed on thebottom of the inner tub. The strainer prevents direct contact with thebottom wall of the inner tub and also functions to obscure dirt or skinparticles that may be otherwise visible in the bottom of the paraffinbath.

The therapeutic paraffin bath of the present invention preferablyincludes a lid that may be locked in place over the inner tub. The lidis preferably mechanically locked to the inner tub of the paraffin bathas the bath is heated or when the bath is transported.

According to the invention, a paraffin bath apparatus for meltingparaffin is provided. A paraffin bath includes a housing having a base,a sidewall and an upper opening. An inner tub is formed of polymericmaterial that is selected for high temperature performance and isgenerally cup shaped having a bottom wall, an upstanding wall and anopen top. The inner tub is received within the upper opening of thehousing with the bottom wall overlying the base. Paraffin is supplied inthe inner tub. The heating element is disposed between the inner tub andthe housing. The heating element provides heat through the inner tubsufficient to melt the paraffin but below the temperature that wouldadversely affect the polymeric material forming the inner tub. Anadjustable thermostatic sensor is disposed between the inner tub and thehousing that is electrically connected to the heating element to controlthe heat provided to the inner tub. A thermal fuse is electricallyconnected to a circuit including the heating elements. The thermal fusedisables the heating elements when the temperature of the space betweenthe housing and the inner tub exceeds a predetermined temperature.

The heating element may also include a base heating element locatedbetween the base and the bottom wall and a side heating element locatedbetween the side wall and the upstanding wall. The base heating elementand the side heating element are formed as separate parts. The heatingelements are preferably braided metallic members. The braided metallicmember is contained between two layers of foil that aid in dispersingheat. The thermostatic sensor is remotely mounted relative to the innertub and is connected to a thermally conductive element that contacts aportion of the inner tub.

The inner tub is preferably of formed polypropylene but may also beformed of another temperature resistant polymer.

The present invention may also be characterized as a paraffin bathapparatus for melting paraffin that is provided with a temperatureindicating element indicating the temperature of the paraffin melted inthe apparatus. A housing having a base and an upper opening receives aninner tub that is generally cup-shaped and has a bottom wall and an opentop. The inner tub is received within the upper opening of the housingwith the bottom wall of the inner tub overlying the base. Paraffin issupplied to the inner tub for melting. A heating element is disposedbetween the inner tub and housing. The adjustable thermostatic sensor isdisposed between the inner tub and the housing. The temperatureindicating element is disposed in the inner tub and placed in contactwith paraffin in the inner tub at a location that is not directlyopposite a heating element. The temperature indicating element providesa visual indication that the paraffin in the inner tub is within apredetermined temperature range. The visual indication is visiblethrough the paraffin after the paraffin is melted.

The temperature indicating element is preferably secured to a strainerthat is disposed in the tub on the bottom wall. The temperatureindicating element may alternatively be secured to the inside of theinner tub at a location that is not directly opposite a heating element.The temperature indicating element is a color changing strip thatincludes a chemical that changes colors to indicate that the paraffin iswithin the predetermined temperature range.

These and other aspects and objects of the present invention will bemore clearly understood in view of the attached drawings and in light ofthe following detailed description of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a paraffin bath made inaccordance with the present invention.

FIG. 2 is a transverse cross-sectional view taken through the center ofthe paraffin bath shown in FIG. 1.

FIG. 3 is a longitudinal cross-sectional view taken through the centerof the paraffin bath.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to FIG. 1, a paraffin bath appliance 10 of the presentinvention is shown in an exploded perspective view. Assembly of theparaffin bath appliance is shown in FIGS. 2 and 3. The principalstructural components of the paraffin bath appliance 10 include ahousing 12 in which an inner tub 14 is received. A strainer 16 isloosely located in the inner tub 14. A lid 18 is provided to cover theinner tub 14.

The housing 12 includes a base 22 and a side wall 24 extending aroundthe periphery of the base 22. The housing defines an upper opening 26 onits upper end.

The inner tub 14 is preferably formed of a high temperature resistantpolymeric material such as polypropylene. The inner tub 14 has a bottomwall 30 and an upstanding wall 32 extending upwardly from the peripheryof the bottom wall 30. The upstanding wall 32 defines an open top 34 atits upper end.

A temperature indicating element 38 is provided on the strainer 16. Thetemperature indicating element 38 is formed of a polymeric materialhaving a material contained therein that changes color when apredetermined temperature is reached. The strainer 16 has a plurality ofslots 40 that permit paraffin to circulate through the strainer 16. Anydirt, skin particles or other debris fall through the slots 40 to thebottom of the inner tub 14. Flanges 42 extend downwardly from portionsof the periphery of the strainer 16 that hold the strainer 16 in aspaced relationship relative to the bottom wall 30 of the inner tub 14.

Side heating element 44 extends in a helical fashion around theupstanding wall 32 of the inner tub 40. The heating element 44 islocated within the housing 12 adjacent the side wall 24. A base heatingelement 46 is arranged in a serpentine fashion between the base 22 andbottom wall 30 and is secured to the bottom wall 30 of the inner tub 14.Side foil sheets 50 are provided on the inner and outer sides of theside heating element 44. Base foil sheets 52 are provided on the upperand lower surfaces of the base heating element 46. The side heatingelement 44 and base heating element 46 are preferably formed of abraided metal of preferably copper or aluminum that is durable and longlasting. The side and base foil sheets 50 and 52 are provided to evenlydistribute the heat generated by the side and base heating elements 44and 46 around and under the inner tub 14.

A knob 54 for an adjustable thermostat 56 may be turned by a user tocontrol the temperature of the paraffin in the paraffin bath appliance10. The adjustable thermostat 56 is provided to control the heatingprocess and provide a mechanism for sensing the temperature of the innertub 14.

A thermal fuse 58 is provided in the electrical circuit including theside and base heating elements 44 and 46 so that if the temperaturewithin the housing 12 exceeds an upper limit the current supplied to theheating elements 44 and 46 will be interrupted. The thermal fuse 58 isreceived in a thermal fuse clip 60 and is preferably replaceable so thatthe unit may be serviced. Conductive element 62 is a metal stripselected for its thermally conductive properties and is secured to thebottom wall 30 of the inner tub 40 to sense the temperature of the innertub 14 and provide a thermal input to the thermostat 56 that is slightlyspaced from the inner tub 14 and mounted on the housing 12.

A strain relief 64 is provided in the rear of the side wall 24. Thestrain relief 64 is provided to protect and retain the power cord.

Lights 68 are provided between the housing 12 and inner tub 14 on thefront portion of the side wall 24 with one indicating that the bath isturned on and the other indicating that the thermostat has openedindicating that the bath is at the desired temperature.

Referring now to FIGS. 2 and 3, the assembled paraffin bath appliance 10is shown in transverse and longitudinal cross-sections, respectively.The housing 12 has rubber feet 72 on the bottom of the base 22. The feetare located at the base of faster receiving posts 74.

A downwardly extending flange 76 extends about the open top 34 of theinner tub 14. The flange 76 is received in a top groove 78 formed aboutthe upper opening 26 of the housing 12. The flange 76 and groove 78 forma seal between the housing 12 and the inner tub 14. Screws 80 areprovided to securely fasten the housing 12 and inner tub 14 together.

While not shown, electrical wires connect the thermostat 56, thermofuse58, heating elements 44, 46 and lights 68 in a conventional circuit.

In an alternative embodiment, temperature indicating element 38 could beaffixed to the inner tub 14 on the side wall 24 thereof. The temperatureindicating element 38 should be preferably located on a portion of theupstanding wall 32 that is not directly opposite the side heatingelement 44. Heat radiated by the heating element should not be allowedto distort the indication provided by the temperature indicating element38 that is intended to sense the temperature of the paraffin in theinner tub 14.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the invention.

What is claimed is:
 1. A paraffin bath apparatus for melting paraffincomprising: a housing having a base, a side wall and an upper opening;an inner tub being formed of a polypropylene polymeric material that isselected for high temperature performance and is generally cup shapedhaving a bottom wall, an upstanding wall and an open top, the inner tubbeing received within upper opening of the housing with the bottom walloverlying the base, paraffin is supplied to the inner tub; a heatingelement disposed between the inner tub and the housing, the heatingelement providing heat through the inner tub sufficient to melt theparaffin but below the temperature that would adversely effect thepolypropylene polymeric material forming the inner tub; and anadjustable thermostat disposed between the inner tub and the housingthat is electrically connected to the heating element to control theheat provided to the inner tub wherein the thermostat includes athermostatic sensor remotely mounted relative to the inner tub and isconnected to a thermally conductive element that directly contacts anouter surface of the inner tub bottom wall.
 2. The paraffin bathapparatus of claim 1 wherein a thermal fuse is provided between thehousing and the inner tub and is electrically connected to a circuitincluding the heating element and that disables the heating element whenthe temperature of the space between the housing and the inner tubexceeds a predetermined temperature.
 3. The paraffin bath apparatus ofclaim 1 wherein the heating element includes a base heating elementlocated between the base and the bottom wall and a side heating elementlocated between the side wall and the upstanding wall, the base heatingelement and side heating element being separate heating elements.
 4. Theparaffin bath apparatus of claim 3 wherein the side heating element isretained by at least one layer of foil.
 5. A paraffin bath apparatus formelting paraffin comprising: a housing having a base, a side wall and anupper opening; an inner tub being formed of a polypropylene polymericmaterial that is selected for high temperature performance and isgenerally cup shaped having a bottom wall, an upstanding wall and anopen top, the inner tub being received within upper opening of thehousing with the bottom wall overlying the base, paraffin is supplied tothe inner tub wherein the open top of the inner tub and the upperopening of the housing have cooperating elements that align the open topand upper opening about their periphery, the cooperative elementscomprising a flange and a groove, wherein the flange is received in thegroove to connect the housing and the inner tub; a first set offasteners are provided to secure the housing and inner tub together atthe upper opening and the open top and a second set of fasteners arealso provided to secure the base of the housing to the bottom wall; anda heating element disposed between the inner tub and the housing, theheating element providing heat through the inner tub sufficient to meltthe paraffin but below the temperature that would adversely effect thepolypropylene polymeric material forming the inner tub.
 6. The paraffinbath apparatus of claim 5 wherein a metallic sheet is secured to theinner tub and is generally disposed between the heating element and thehousing.
 7. The paraffin bath apparatus of claim 5 wherein the heatingelement includes at least a base heating wire and a side heating wire.